The present invention relates to a new type of filter for the printing of color photographic films.
As is known in the art, a subtractive filter is a device formed of three filters, each colored in one of the three complementary colors (yellow, magenta, cyan) arranged in the beam of light coming from a source of white light and adapted to correct the dominances of colors coming either from said light or from the use of different printing processes, films or papers. Each of these three filters is adjusted as a function of the density of light which is desired. As is known, this density d is equal to: EQU d=log T/1
in which T is the transmission of the light. It follows therefore, if d=0 there is maximum transmission since there is no filtering. It also follows that the more the density increases the more the light is filtered. In practice, the filtering is generally limited to a value of approximately 1.4.
Because such subtractive filters are well known in the art they will not be described in detail. At present there are several types of filters of very different construction; each of which has its advantages and its drawbacks, including in particular the device disclosed in U.S. Pat. No. 4,168,904.